Targeting the
Sharpshooter

Sharpshooters becoming targets is
unusual, but through an ambitious new research program that is whats
happening to the glassy-winged sharpshooter, an insect pest costing California
vineyards more than $14 million annually. The sharpshooter carries the
bacterium Xylella fastidiosa, which causes incurable Pierces
disease of grapevines.

In Argentina, scientists at the ARS South American Biological Control
Laboratory at Hurlingham are investigating beneficial wasps that are powerful
natural enemies of the sharpshooter. These wasps are egg parasitoids, meaning
they lay their eggs inside the sharpshooter eggs. The wasp young then feast on
the sharpshooter young.

Helping to fund the Hurlingham studies is the ARS
Beneficial Insects Research
Unit in Weslaco, Texas. In addition, Weslaco researchers are seeking
potential biological combat agents from other regions, particularly another egg
parasitoid found in south Texas and northeastern Mexico. This parasitoid may be
partially responsible for the lack of glassy-winged sharpshooters in those
regions, according to Walker A. Jones, leader of the Weslaco unit.

Another technique for fending off the sharpshooters is coating the
grapevines with white clay, which makes the vines inhospitable to the pests.
ARS entomologist Gary J. Puterka co-developed the white clay coating, now sold
by Engelhard
Corp. under the trade name, Surround. Puterka works at the ARS
Appalachian Fruit Research Station in
Kearneysville, W.Va. At test vineyards in Kern County, Calif., Puterka and
colleagues found the white clay coating outperformed insecticides, as growers
needed only three clay coatings in contrast to six insecticide sprayings.